Gas valves are commonly used in semiconductor processing systems as inlets and outlet for the introduction of gases in to processing chambers, and for providing the capability of purging and vacuum testing the process system. In some semiconductor processes, a plurality of process chambers or reactors may be sequentially connected to provide for a series of processing steps without removing the semiconductor devices from the series of process chambers. With prior art valves it is not possible to perform simultaneous purge and/or vacuum operation on the same line.